1. Field of the Invention
The present invention relates to an electrochemical gas-detection device which is useful for detecting carbon monoxide gas (hereinafter referred to as CO) and/or hydrogen gas (hereinafter referred to as H.sub.2) in the atmosphere.
2. Description of the Prior Art
Semiconductor sensors have widely been used for detecting gas in industry and in the home. However, these sensors have the disadvantages that the measurement precision thereof is liable to be affected by water vapor or other ambient gases, and that the sensitivity thereof is apt to change with time, etc. Accordingly, an electrochemical gas-detection method has been proposed in which chronoamperometry is used since it has a reliable measurement precision and sensitivity (see Japanese Official Gazettes for Laying-open of Patent Application No. 53-140098 (1978), Laying-open of Patent Application No. 54-148588 (1979), and Laying-open of Utility-Model Application No. 54-167790 (1979)). This method has the advantage that it is possible to make the quantitative analysis of the gas components, since the electrolytic current is proportional to the concentration of the gas components to be detected.
The electrochemical gas-detection method so far proposed has the disadvantage, however, when the gas component to be detected comes into contact with working electrode and reference electrode of the gas detecting device, the device is immediately responsive to H.sub.2 and CO. This is because the working electrode and reference electrode of the conventional device have the same sensitivity to CO and H.sub.2.
The conventional device cannot be used for detection of fuel gas leakage or detection of incomplete combustion. Accordingly the device cannot distinguish the gas leakage from combustion.